Antigen exposure chamber system

ABSTRACT

An object of the present invention is to solve the problems in conventional art antigen exposure chambers, and specifically, to provide an antigen exposure chamber system capable of simultaneously exposing a large number of test objects in a chamber to a uniform antigen (pollen, mite or house dust, etc.) in all seasons. In order to achieve the above object, in an antigen exposure chamber system according to the present invention, an outdoor air is supplied via an outdoor air diffuser  2  provided in a ceiling surface of an exposure chamber  1  into the exposure chamber from the ceiling surface of the exposure chamber in a horizontal direction, a fan unit  15 , including a supply port and a suction port, is provided in each of the four corners of the exposure chamber to provide a circulating flow of air flowing with circulation in the horizontal direction in the exposure chamber, an air exhaust port  4  is provided at a floor surface of the exposure chamber to exhaust an air from the floor surface of the exposure chamber, an antigen is supplied from an antigen supply device to the outdoor air diffuser provided on the ceiling surface so that the antigen is mixed with the outdoor air, and a uniform concentration antigen exposure is enabled by the circulating flow of air.

TECHNICAL FIELD

The present invention relates to an antigen exposure chamber system forexposing subjects to an antigen.

BACKGROUND ART

Antigen exposure chamber systems configured so as to supply apredetermined amount of antigen to expose a subject to the antigen havebeen used for experiments and researches relating to diseases such asallergy.

Conventional antigen exposure chamber systems include ones provided witha ceiling air supply port and a ceiling air exhaust port at the ceilingof the chamber, or an air supply port at the ceiling of the chamber andan air exhaust port at the lower portion of the chamber walls, therebygenerating an air flow flowing between the air supply port and the airexhaust port and mixing an antigen supplied from the outside of thechamber into this air flow. However, each of them has an extremelynon-uniform antigen concentration distribution in the chamber (forexample, see Non-Patent Document 1).

Furthermore, there are no measures to prevent an antigen from flowingout of the chamber more than making the chamber pressure to be anegative pressure, which is extremely insufficient for preventing anantigen from flowing out of the chamber, so there has been thepossibility that an antigen flows to the outside of the antigen exposurechamber.

Also, when a measuring device is installed outside the exposure chamber,a sampling tube is used to take sample antigen concentrations in thechamber. However, there are various kinds of materials for samplingtubes for the conventional antigen exposure chamber systems, and thereare no fixed arrangement routes for such sampling tubes, andcompensation of the measured values has not been made. Accordingly,there is a problem in that the loss of antigen particles is so largethat an accurate concentration measurement cannot be conducted,depending on the material, the length or the bent portion count of thetube.

-   Patent Document 1: None-   Non-Patent Document 1: N. Krug et al., Validation of an    environmental exposure unit for controlled human inhalation studies    with grass pollen in patients seasonal allergic rhinitis, Clinical &    Experimental Allergy, Vol. 33, No. 12, p.p. 1667-1674, December 2003

DISCLOSURE OF THE INVENTION Problem to be Solved by the Invention

An object of the present invention is to solve the problems in theaforementioned conventional art antigen exposure chambers, and morespecifically to provide an antigen exposure chamber system capable ofsimultaneously exposing a large number of subjects in a chamber to auniform antigen (pollen, mite or house dust, etc.) in all seasons.

Means for Solving the Problem

In order to achieve the above object, in an antigen exposure chambersystem according to the present invention, an outdoor air is suppliedvia an outdoor air diffuser provided in a ceiling surface of an exposurechamber into the exposure chamber from the ceiling surface of theexposure chamber in a horizontal direction, a fan unit, including asupply port and a suction port, is provided in each of the four cornersof the exposure chamber to provide a circulating flow of air flowingwith circulation in the horizontal direction in the exposure chamber, anair exhaust port is provided in a floor surface of the exposure chamberto exhaust an air from the floor surface of the exposure chamber, anantigen is supplied from an antigen supply device to the outdoor airdiffuser provided in the ceiling surface so that the antigen is mixedwith the outdoor air, and a uniform concentration antigen exposure isenabled by the circulating flow of air.

The antigen exposure chamber system according to the present inventionfurther comprises an antigen concentration measuring device formeasuring an antigen concentration within the antigen exposure chamber.When the antigen concentration measuring device is installed outside thechamber, it is preferable to take a sample air within the chamber bymeans of the sampling tube, and to minimize a measurement error causedby the sampling tube by using PVC (polyvinyl chloride) as the materialfor the sampling tube and providing a fixed arrangement route for thesampling tube.

The antigen exposure chamber system according to the present inventionfurther comprises a guard room surrounding the antigen exposure chamber,wherein a chamber pressure within the antigen exposure chamber is madeto be a negative pressure, or the chamber pressure is made to be apositive pressure and the guard room is made to have a negativepressure, and an air shower is provided at an entrance/exit, therebypreventing the antigen from leaking out of the chamber.

It is preferable that the air flow rate and velocity of the introducedoutdoor air and the circulating air flow are controlled so that subjectsdo not feel draft (ventilation).

Furthermore, it is preferable that an outdoor air introduction system isprovided with means for adjusting a temperature and humidity of theintroduced outdoor air to provide a set temperature and humidity withinthe antigen exposure chamber, and a filter for removing a particulatesubstance, and an activated carbon filter for removing a gaseouscontaminant (NO_(x), SO_(x), VOC or aldehydes, etc.)

It is preferable that the air exhaust system is also provided to afilter for removing the antigen in the exhaust air.

Effects of the Invention

As a result of employing the above configuration, the antigen exposurechamber system according to the present invention is capable ofuniformizing the antigen concentrations in the chamber with a variationof around ±10%.

Furthermore, it is capable of minimizing the flow of the antigen in thechamber to the outside, and also capable of accurately measuring anantigen concentration within the chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a side view and plain view of a schematic configuration ofan embodiment of an antigen exposure chamber system according to thepresent invention;

FIG. 2 shows a side view and plain view of a schematic configuration ofanother embodiment of an antigen exposure chamber system according tothe present invention;

FIG. 3 is a diagram indicating the measurement results of an antigenconcentration distribution in the chamber according to the embodimentshown in FIG. 1; and

FIG. 4 is a diagram indicating the measurement results of an air flowvelocity distribution in the chamber according to the embodiment shownin FIG. 1; and

FIG. 5 is a chart showing the differences in measurement resultsaccording to the type of tube material.

DESCRIPTION OF SYMBOLS

-   1, 1′: antigen exposure chamber,-   2: outdoor air diffuser, 3: antigen,-   4: air exhaust port, 5: supply air filter unit,-   6: exhaust air filter unit, 7: pre-air filter,-   8: medium-efficiency air filter,-   9: cold/hot water coil, 10: pre-heater,-   11: activated carbon filter, 12: HEPA filter,-   13: medium-efficiency air filter, 14: HEPA filter,-   15,15′: fan unit, 16: sampling tube,-   17: antigen concentration measuring device,-   18: circulating air flow duct

BEST MODE FOR CARRYING OUT THE INVENTION

FIG. 1 shows a side view and plain view of a schematic configuration ofan embodiment of an antigen exposure chamber system according to thepresent invention. Generally, an antigen exposure chamber 1 isconfigured so as to blow a certain high concentration antigen 3, such aspollen, mite or house dust, etc., supplied from an antigen supply device(not shown) into an outdoor air supplied from an outdoor air diffuser 2provided at the center of its ceiling to mix them, and to make the aircontaining the thus mixed antigen permeate the chamber, and to exhaustthe air from air exhaust ports 4 provided at the floor surface of theantigen exposure chamber.

The outdoor air to be supplied to the outdoor air diffuser 2 is suppliedvia a supply air filter unit 5. The supply air filter unit 5 includes apre-air filter 7, a medium-efficiency air filter 8, a cold/hot watercoil 9, a pre-heater 10, an activated carbon filter 11 and a HEPA(high-efficiency particulate air) filter 12.

Meanwhile, the exhaust air from the air exhaust ports 4 is dischargedvia an exhaust air filter unit 6. The exhaust air filter unit 6 includesa medium-efficiency air filter 13 and a HEPA filter 14.

As shown in the FIG. 1 plain view, the air exhaust ports 4 are providedat one central point of the chamber and at four points on a concentriccircle with a diameter of ⅖r to 1r where r is the radius of an inscribedcircle of the chamber with the aforementioned central point as itscenter.

As shown in the Figure, a total of twelve fan units 15 are provided atthe four corners of the antigen exposure chamber 1. Each fan unit 15 isprovided with an air suction port and an air supply port. Accordingly,as can be seen from the plain view in the lower portion of FIG. 1, thesuction and supply of air in the fan units 15 generates a circulatingflow of air circulating in a counterclockwise direction in FIG. 1. Thiscirculating air flow makes the air flow containing the antigen uniformlypermeate the entire antigen exposure chamber. The velocity of thecirculating air flow is controlled to a level that subjects in thechamber do not feel draft.

Although it is preferable that an antigen concentration within theantigen exposure chamber is directly measured by placing an antigenconcentration measuring device 17 within the antigen exposure chamber 1,in the present embodiment, it is measured by the antigen concentrationmeasuring device 17 via a sampling tube 16. The antigen concentrationmeasuring device 17 controls the antigen supply device based on themeasured antigen concentration so as to constantly provide apredetermined antigen concentration. A measurement error caused by thesampling tube is minimized by using PVC (polyvinyl chloride) as amaterial for the sampling tube and providing a fixed arrangement routefor the sampling tube.

With the aforementioned configuration, the antigen exposure chamber 1has an atmosphere with an extremely-uniform antigen concentrationdistribution, enabling exposing a plurality of subjects to an antigen atthe same time. In the antigen exposure chamber, the chamber pressure ismade to be a negative pressure, or the chamber pressure is made to be apositive pressure and a guard room is made to have a negative pressure,and furthermore, an air shower (not shown) is provided at anentrance/exit of the chamber, preventing the antigen from leaking out ofthe chamber.

Although in the present embodiment, the antigen is supplied toward theoutdoor air diffuser 2 from the inside of the chamber, it may besupplied at a position above the outdoor air diffuser 2 outside thechamber.

FIG. 2 shows a side view and plain view of a schematic configuration ofanother embodiment of an antigen exposure chamber system according tothe present invention. The present embodiment is configured so that fanunits are installed outside the chamber. As can be seen from the Figure,one fan unit 15′ is provided at each of the upper external four cornersof the antigen exposure chamber 1′ as shown in the FIG. 2 plain sideview. Furthermore, at each of the internal four corners of the antigenexposure chamber 1′, a circulating air flow duct 18 that guides the airflow caused by the fan unit is provided. The circulating air flow duct18, as shown in the side view, generates an air flow going from thelower portion to the upper portion within the circulating air flow duct18, going through the fan and then going from the upper portion to thelower portion as a result of rotation of the fan unit 15′, and as shownin the plain view, it is provided with openings so as to generate an airflow circulating in a counterclockwise direction, which goes through thecirculating flow duct in a horizontal direction. With suchconfiguration, when the fan units are activated, the flow of aircontaining the antigen uniformly permeates the entire antigen exposurechamber, forming an exposure space with a predetermined antigenconcentration distribution. The velocity of the circulating air flow iscontrolled to a level that subjects within the chamber do not feeldraft, as in the preceding embodiment.

The other components of the antigen exposure chamber 1′ are similar tothose in the antigen exposure chamber system shown in FIG. 1, andaccordingly, are provided with the same reference numerals as those inFIG. 1. Since the functions of these components are also the same asthose in FIG. 1, the description thereof is omitted.

FIGS. 3 and 4 are diagrams indicating the measurement results of anantigen concentration distribution in the chamber and the measurementresults of an air flow velocity distribution in the chamber according tothe embodiment shown in FIG. 1, respectively. The results exhibit avariation of substantially within ±10%, indicating that the results areremarkably favorable compared to the conventional antigen exposurechamber systems.

Furthermore, FIG. 1 is a chart indicating differences in measuredconcentration value according to the materials for the sampling tube 16,where the ratio r satisfies the following formula:

${{Ratio}\mspace{14mu} r} = {\frac{{Measurement}\mspace{14mu}{value}\mspace{14mu}{when}\mspace{14mu}{the}\mspace{14mu}{tube}\mspace{14mu}{is}\mspace{14mu}{used}}{{Measurement}\mspace{14mu}{value}\mspace{14mu}{when}\mspace{14mu}{the}\mspace{14mu}{tube}\mspace{14mu}{is}\mspace{14mu}{not}\mspace{14mu}{used}} \times 100\mspace{11mu}(\%)}$

Table 1 is a chart indicating differences and variations in measurementresults according to the sampling tube lengths and the lapse times.

TABLE 1 Effect of the Length of the Sampling Tube (PVC) (Ratio r) LapseTime Tube Length 2 h 4 h 6 h 8 h  6 m 94 94 94 93 10 m 79 81 81 83

${{Ratio}\mspace{14mu} r} = {\frac{{Measurement}\mspace{14mu}{value}\mspace{14mu}{when}\mspace{14mu}{the}\mspace{14mu}{tube}\mspace{14mu}{is}\mspace{14mu}{used}}{{Measurement}\mspace{14mu}{value}\mspace{14mu}{when}\mspace{14mu}{the}\mspace{14mu}{tube}\mspace{14mu}{is}\mspace{14mu}{not}\mspace{14mu}{used}} \times 100\mspace{11mu}(\%)}$

These charts show that it is preferable to use vinyl chloride for thesampling tube material because it has only a small effect on theconcentration measurement results. Also, they show that it is preferableto use a shorter tube because it has a smaller effect on theconcentration measurement results.

INDUSTRIAL APPLICABILITY

Although the antigen exposure chamber system according to the presentinvention has been described above with reference to embodimentsthereof, the present invention is not limited to these embodiments, andvarious alterations and modifications can be made within the technicalidea of the present invention.

1. An antigen exposure chamber system for exposing a subject to anantigen, the system comprising: an antigen exposure chamber having aceiling, a floor, and four corners, said antigen exposure chamber havinga square horizontal cross section and a center vertical axis passingthrough the center of the antigen exposure chamber; only a singleoutdoor air inlet diffuser provided in a ceiling surface at the centervertical axis of the antigen exposure chamber so as to supply outdoorair out from the outdoor air diffuser in the ceiling surface into theantigen exposure chamber, the air diffuser being configured to diffuseoutdoor air in a horizontal direction within the antigen exposurechamber; a fan unit provided at each of the four corners of the antigenexposure chamber, each fan unit having a supply port and a suction portand providing a circulating flow of air flowing with circulation in thehorizontal direction within the antigen exposure chamber, thecirculating flow of air being controlled to a level that the subjectdoes not feel a draft of blown air; and five air exhaust outlet portspositioned along the floor of the antigen exposure chamber to carry airfrom the antigen exposure chamber to outside of the chamber, one ofwhich is provided at a central point of the floor along the centralvertical axis of the antigen exposure chamber below the air inletdiffuser, and four others of the air exhaust outlet ports beingsymmetrically provided at points on a concentric circle with a diameterof ⅖r to r, where r is a radius of the inscribed circle of the chamberwith the center vertical axis as its center, so as to exhaust air fromthe floor surface of the antigen exposure chamber, wherein the antigenis supplied from an antigen supply device so as to mix the antigen withthe outdoor air by blowing the antigen into the outdoor air suppliedfrom the outdoor air inlet diffuser provided in the ceiling surface intothe antigen exposure chamber, and a uniform concentration antigenexposure is enabled by the circulating flow of air; wherein each of theoutdoor air diffuser, the air exhaust ports, the fan units and theantigen supply device is symmetrically positioned horizontally infore-and-aft and right-and-left directions about the center verticalaxis passing through the center of the antigen exposure chamber.
 2. Theantigen exposure chamber system according to claim 1, further comprisinga sampling port for measuring an antigen concentration within theantigen exposure chamber, wherein a sample air is guided to an antigenconcentration measuring device installed outside the antigen exposurechamber, via a tube formed of polyvinyl chloride (PVC).
 3. The antigenexposure chamber system according to claim 1, further comprising a guardroom surrounding the antigen exposure chamber, wherein a chamberpressure within the antigen exposure chamber is made to be a negativepressure, or the chamber pressure is made to be a positive pressure andthe guard room is made to have a negative pressure.
 4. The antigenexposure chamber system according to claim 1, wherein a system forintroducing the outdoor air into the antigen exposure chamber isconnected to a supply air handling unit including means for adjusting atemperature and humidity of the introduced outdoor air, a filter forremoving a particulate substance, and an activated carbon filter forremoving a gaseous contaminant, and the air exhaust port is connected toan exhaust air filter unit including a HEPA filter for removing theantigen in the exhaust air.
 5. The antigen exposure chamber systemaccording to claim 4, wherein the gaseous contaminant includes NOx, SOx,VOC or aldehydes.
 6. An antigen exposure chamber system for exposing asubject to an antigen, the system comprising: an antigen exposurechamber having a ceiling, a floor, four corners, and a center verticalaxis passing through the center of the antigen exposure chamber; anoutdoor air inlet diffuser provided in a ceiling surface at the centervertical axis of the antigen exposure chamber positioned so as to supplyoutdoor air through the outdoor air diffuser in the ceiling surface intothe antigen exposure chamber, the air diffuser being configured todiffuse outdoor air in a horizontal direction within the antigenexposure chamber; means for circulating air in the chamber at a levelwherein a person within the antigen exposure chamber does not feel adraft of blown air, said means comprising a fan unit provided at each ofthe four corners of the antigen exposure chamber, each fan unit having asupply port and a suction port and providing a circulating flow of airflowing with circulation in the horizontal direction within the antigenexposure chamber, the fan units being symmetrically positionedhorizontally in a fore-and-aft and a right-and-left direction about thevertical axis passing through the center point of the antigen exposurechamber; and five air exhaust outlet ports positioned along the floor ofthe antigen exposure chamber, one of which is provided at a centralpoint of the floor along the central vertical axis of the antigenexposure chamber below the air inlet diffuser, and four others of theair exhaust outlet ports being symmetrically provided at points on aconcentric circle with a diameter of ⅖r to r, where r is a radius of theinscribed circle of the chamber with the center vertical axis as itscenter, so as to exhaust air from the floor surface of the antigenexposure chamber, and an antigen supply device for supplying the antigenby blowing the antigen into the outdoor air supplied from the outdoorair inlet diffuser, the antigen supply device being positioned so as tomix the antigen with the outdoor air near the ceiling surface in theantigen exposure chamber, wherein a uniform concentration antigenexposure is enabled by the circulating flow of air.
 7. The antigenexposure chamber system of claim 6 wherein the antigen exposure chamberhas a square horizontal cross section.
 8. The antigen exposure chambersystem of claim 6 comprising only one said outdoor air inlet diffuser.